hey ...

both are conifers.. there is a very active conifer forum .. post where it makes you happy ...

link below.. intro to conifers ... all conifs have an annual growth rate ... and they will grow at that rate for decades ... size estimates are at 10 years.. and they continue until they double in 20 years ... etc ..

use the database at the link.. insert the names you have into the cultivar line.. and it SHOULD give you its annual growth rate ...

given the annual growth rate ... spacing simply depends on how long you want to wait.. until they fill in ...

good luck

ken

Here is a link that might be useful: link

Annual growth rate for both is 4-8". And as shrubs, there is a limit to how large they will get. But they are spreading cultivars (nearly twice as wide as tall) and too close planting will create shaded or competing conditions that can cause die out of foliage and may even create conditions desirable to the spread of diseases. Better to space them at their estimated mature spread (~6-8') and deal with the blanks with mulch until they begin to fill in.

Here, one sees established plantings of Juniperus chinensis such as you describe in many older neighborhoods (a much more popular planting of several decades ago compared to now). Often these plantings have been butchered by severe pruning simply because the plants have outgrown their position and are interferring with walkways or driveways, etc. Much better to space out properly to begin with than to deal with an overgrown jungle a few years down the road.